Three-Dimensional Self-Supporting Ti₃C₂ with MoS₂ and Cu₂O Nanocrystals for High-Performance Flexible Supercapacitors

The three-dimensional (3D) architecture of electrode materials with excellent stability and electrochemical activity is extremely desirable for high-performance supercapacitors. In this study, we develop a facile method for fabricating 3D self-supporting Ti₃C₂ with MoS₂ and Cu₂O nanocrystal composites for supercapacitor applications. MoS₂ was incorporated in Ti₃C₂ using a hydrothermal method, and Cu₂O was embedded in two-dimensional nanosheets by in situ chemical reduction. The resulting composite electrode showed a synergistic effect between the components. Ti₃C₂ served as a conductive additive to connect MoS₂ nanosheets and facilitate charge transfer. MoS₂ acted as an active spacer to increase the interlayer space of Ti₃C₂ and protect Ti₃C₂ from oxidation. Cu₂O effectively prevented the collapse of the lamellar structure of Ti₃C₂-MoS₂. Consequently, the optimized composite exhibited an excellent specific capacitance of 1459 F g^-1 at a current density of 1 A g^-1. Further, by assembling an all-solid-state flexible supercapacitor with activated carbon, a high energy density of 60.5 W h kg^-1 was achieved at a power density of 10³ W kg^-1. Additionally, the supercapacitor exhibited a capacitance retention of 90% during 3000 charging-discharging cycles. Moreover, high mechanical robustness was retained after bending at different angles, thereby suggesting significant potential applications for future flexible and wearable devices.